The present invention relates to sanding blocks, and more specifically, to hand-held sanding blocks that are readily conformable to curved or flat surfaces.
In the market place today, there are a wide variety of hand-held sanding devices useful for smoothing and polishing a rough or irregular surface. In this regard, a particularly common type of hand-held sanding device is a wood block having a piece of sandpaper wrapped about its exterior. Another common type of hand-held sanding device is a shaped block made of rubber or other resilient material, and which secures a piece of sandpaper along its bottom surface by means of holding clamps or sharp projections. Although both of these common hand-held sanding devices work well for flat surfaces, they do not work particularly well for curved surfaces. In addition, such sanding devices also generally require the cutting and trimming of standard size sheets of sandpaper to an appropriate size.
In short, the above-mentioned common sanding blocks have relatively large, flat sandpaper support surfaces which do not satisfactorily conform to the shape of curved surfaces. Thus, the use of such common sanding blocks on curved surfaces often results in uneven sanding; mainly because such blocks are not bendable to the curvature of the surface being sanded, and because excessive pressure is often applied to some portions of the surface being sanded. Moreover, the application of excessive pressure may result in over sanding and rapid deterioration of the sandpaper, which, in turn, may damage the underlying surface. Concomitantly, common sanding blocks typically under utilize standard size sheets of sandpaper (dimensions of 8.5xe2x80x3xc3x9711xe2x80x3) in that such sheets must be cut and/or trimmed to fit the sanding block""s support surface; such cutting often results in usable scrap material.
A common situation where curved and flat surfaces are in need of sanding involves the body repair of automobiles prior to repainting. Although the sanding of automobiles has been practiced for a long time, the problems associated therewith are numerous. For example, some automobile body parts are relatively smooth, but have sloping curves, and are thus difficult to sand evenly (e.g., conventional sanding devices often result in a xe2x80x9cripplingxe2x80x9d effect along the surface being sanded). Other body parts are flat, but nevertheless need to be sanded without scratching the surrounding areas (such as the painted surfaces between tail lights and the like). Because of these problems, automobiles are often finish sanded by hand (i.e., sandpaper supported by the hand and digits of an individual laborer). For example, it is currently a common practice for laborers in automobile repair shops to use two xe2x80x9cpaint sticksxe2x80x9dstacked together as a support structure for a piece of sandpaper. Such paint sticks are cumbersome to use, have a tendency to form a rippling effect along the surface being sanded, and under utilizes the full sanding surface available with a standard sheet of sandpaper.
Accordingly, there is a need in the art for hand-held sanding blocks that are readily conformable to curved or flat surfaces, and which better utilizes standard sheets of sandpaper. The present invention fulfills these needs and provides for further related advantages.
In brief, the present invention is directed to hand-held sanding blocks that are readily conformable to curved or flat surfaces. In one embodiment, the hand-held sanding block is an elastomeric sanding block conformable to curved or flat surfaces, wherein the elastomeric sanding block has a Shore A hardness ranging from about 45 to about 90, and wherein the elastomeric sanding block is made from a polymeric composition formulated from a plurality ingredients. The plurality of ingredients includes, among other things, an admixture of an ethylene-vinyl acetate copolymer and a metallocene catalyzed ethylene-xcex1-olefin copolymer (wherein the admixture is in an amount that ranges from about 50 to about 100 percent of the composition by weight), and a blowing agent (e.g., an azodicarbonamide compound). In other embodiments, the plurality of ingredients further includes one or more of a filler (e.g. calcium carbonate), a processing additive (e.g., stearic acid, zinc oxide, titanium oxide, and an organic peroxide), and an extending oil.
The sanding blocks of the present invention may have cubic rectangular dimensions, preferably such cubic rectangular dimensions have an outer perimeter of about 334 mm (e.g., rectangular dimensions in one preferred embodiment are about 279 mm (L) by about 35 mm (W) by about 20 mm (T)). Further, the sanding blocks of the present invention generally have densities of about 10 to about 30 pounds per cubic foot (PCF), and preferably densities of about 20 pounds per cubic foot (PCF). Further still, the sanding blocks of the present invention have Shore A hardness ranging from about 50 to about 85, and preferable ranging from about 60 to about 75, and even more preferable from about 65 to about 70.
The present invention is also directed to a method for manufacturing an elastomeric sanding block conformable to curved or flat surfaces. In general, the method comprises the steps of: compounding a polymeric composition formulated from a plurality ingredients that include at least an admixture of an ethylene-vinyl acetate copolymer and a metallocene catalyzed ethylene-xcex1-olefin copolymer, wherein the admixture is in an amount that ranges from about 50 to about 100 percent of the composition by weight; combining the polymeric composition with a blowing agent and an organic peroxide cross-linking agent under heat to yield a feedstock; calendering the feedstock to yield a material sheet; thermoforming the material sheet in a mold to yield a foamed material sheet; and cutting the foamed material sheet to yield the elastomeric sanding block.